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NAME
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memdraw, memlalloc, memldelete, memlexpose, memlfree, memlhide,
memline, memlnorefresh, memload, memunload, memlorigin, memlsetrefresh,
memltofront, memltofrontn, memltorear, memltorearn – windows of
memory-resident images
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SYNOPSIS
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#include <u.h>
#include <libc.h>
#include <draw.h>
#include <memdraw.h>
#include <memlayer.h>
typedef struct Memscreen Memscreen;
typedef struct Memlayer Memlayer;
typedef void (*Refreshfn)(Memimage*, Rectangle, void*);
struct Memscreen
{
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Memimage *frontmost; /* frontmost layer on screen */
Memimage *rearmost; /* rearmost layer on screen */
Memimage *image; /* upon which all layers are drawn */
Memimage *fill; /* if non−zero, picture to use when repainting
*/
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};
struct Memlayer
{
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Rectangle screenr; /* true position of layer on screen */
Point delta; /* add delta to go from image coords to screen */
Memscreen *screen; /* screen this layer belongs to */
Memimage *front; /* window in front of this one */
Memimage *rear; /* window behind this one*/
int clear; /* layer is fully visible */
Memimage *save; /* save area for obscured parts */
Refreshfn refreshfn; /* fn to refresh obscured parts if save==nil
*/
void *refreshptr;/* argument to refreshfn */
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};
Memimage* memlalloc(Memscreen *s, Rectangle r, Refreshfn fn, void
*arg, ulong col)
void memlnorefresh(Memimage *i, Rectangle r, void *arg)
int memlsetrefresh(Memimage *i, Refreshfn fn, void *arg)
int memldelete(Memimage *i)
int memlfree(Memimage *i)
int memlexpose(Memimage *i, Rectangle r)
int memlhide(Memimage *i, Rectangle r)
void memltofront(Memimage *i)
void memltofrontn(Memimage**ia, int n)
void memltorear(Memimage *i)
void memltorearn(Memimage **ia , int n)
int memlorigin(Memimage *i, Point log, Point phys)
void memdraw(Image *dst, Rectangle r,
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Image *src, Point sp, Image *mask, Point mp, Drawop op)
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int memload(Memimage *i, Rectangle r,
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uchar *buf, int n, int iscompressed)
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int memunload(Memimage *i, Rectangle r,
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DESCRIPTION
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These functions build upon the memdraw(3) interface to maintain
overlapping graphical windows on in-memory images. They are used
by the kernel to implement the windows interface presented by
draw(3) and window(3) and probably have little use outside of
the kernel.
The basic function is to extend the definition of a Memimage (see
memdraw(3)) to include overlapping windows defined by the Memlayer
type. The first fields of the Memlayer structure are identical
to those in Memimage, permitting a function that expects a Memimage
to be passed a Memlayer, and vice versa. Both structures have
a save field, which
is nil in a Memimage and points to ‘backing store’ in a Memlayer.
The layer routines accept Memimages or Memlayers; if the image
is a Memimage the underlying Memimage routine is called; otherwise
the layer routines recursively subdivide the geometry, reducing
the operation into a smaller component that ultimately can be
performed on a
Memimage, either the display on which the window appears, or the
backing store.
Memlayers are associated with a Memscreen that holds the data
structures to maintain the windows and connects them to the associated
image. The fill color is used to paint the background when a window
is deleted. There is no function to establish a Memscreen; to
create one, allocate the memory, zero frontmost and rearmost,
set fill
to a valid fill color or image, and set image to the Memimage
(or Memlayer) on which the windows will be displayed.
Memlalloc allocates a Memlayer of size r on Memscreen s. If col
is not DNofill, the new window will be initialized by painting
it that color.
The refresh function fn and associated argument arg will be called
by routines in the library to restore portions of the window uncovered
due to another window being deleted or this window being pulled
to the front of the stack. The function, when called, receives
a pointer to the image (window) being refreshed, the rectangle
that has been uncovered,
and the arg recorded when the window was created. A couple of
predefined functions provide built-in management methods: memlnorefresh
does no backup at all, useful for making efficient temporary windows;
while a nil function specifies that the backing store (Memlayer.save)
will be used to keep the obscured data. Other functions may be
provided by the client. Memlsetrefresh allows one to change the
function associated with the window.
Memldelete deletes the window i, restoring the underlying display.
Memlfree frees the data structures without unlinking the window
from the associated Memscreen or doing any graphics.
Memlexpose restores rectangle r within the window, using the backing
store or appropriate refresh method. Memlhide goes the other way,
backing up r so that that portion of the screen may be modified
without losing the data in this window.
Memltofront pulls i to the front of the stack of windows, making
it fully visible. Memltofrontn pulls the n windows in the array
ia to the front as a group, leaving their internal order unaffected.
Memltorear and memltorearn push the windows to the rear.
Memlorigin changes the coordinate systems associated with the
window i. The points log and phys represent the upper left corner
(min) of the window’s internal coordinate system and its physical
location on the screen. Changing log changes the interpretation
of coordinates within the window; for example, setting it to (0,
0) makes the upper left corner
of the window appear to be the origin of the coordinate system,
regardless of its position on the screen. Changing phys changes
the physical location of the window on the screen. When a window
is created, its logical and physical coordinates are the same,
so
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memlorigin(i, i−>r.min, i−>r.min)
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would be a no-op.
Memdraw and memline are implemented in the layer library but provide
the main entry points for drawing on memory-resident windows.
They have the signatures of memimagedraw and memimageline (see
memdraw(3)) but accept Memlayer or Memimage arguments both.
Memload and memunload are similarly layer-savvy versions of loadmemimage
and unloadmemimage. The iscompressed flag to memload specifies
whether the n bytes of data in buf are in compressed image format
(see image(7)).
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SOURCE
SEE ALSO
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